1. Field of the Invention
The present invention relates to a single stage microactuator for multidimensional actuation, and more particularly, to an X-Y stage microactuator for use in a data storage system employing scanning probe microscope (SPM) techniques.
2. Description of the Related Art
A data storage system using SPM techniques mainly includes a medium fo rstorage, an actuator for mounting the medium to a stage and driving it in x and y directions, one or more probes each having a tip for storing or reading information on or from the medium, and a signal processor for processing such information signals. The multiple probes can store or read data at one time, and to accomplish this, the tip of the probe must approach the medium. Thus, the probe requires an actuator and a sensor. The actuator deforms the probe in Z direction so that the probe tip approaches the medium, and the sensor senses the deformation of the probe made according to information stored on the medium and reads the relevant information.
To achieve stage actuation along two or more axes in the X-Y plane, the actuator requires at least three electrodes for unidirectional actuation along one axis and at least five electrodes for bidirectional actuation along one axis.
According to U.S. Pat. No. 5,536,988, a microactuator requiring a plurality of electrodes is fabricated from a crystal structure using a thermal oxidation isolation technique to enable multi-dimensional motion. This approach address the electrode problem associated with multi-dimensional actuation, but the process is complicated.
Unlike this approach, in an article presented by P. F. Indermuehle et al., xe2x80x9cDesign and Fabrication of an Overhanging xy-microactuator With Integrated Tip for Scanning Surface Profiling, Sensors and Actuators A. 43 (1994) pp 346-350, there is a discussion of the use of a single electrode for two-axis actuation although this approach offers a simple process without an isolation process, the use of a single electrode in an actuating part of actuation causes interferences between the two-way actuation. An actuator having the above structure has problems in that the actuator is structurally unstable to allow rotational motion with respect to a vertical axis of an actuating plane such that it cannot be used as an actuator having a large stage for a storage system, and that it suffers from loss of a stage area over the total area of the microactuator due to the length of a spring between the stage and the actuator.
To solve the above problems, it is a first object of the present invention to provide a single-stage microactuator which is capable of multi-dimensional actuation with a single electrode in an actuating part and of simplifying a fabrication process without an isolation process step.
It is a second object to provide a single-stage microactuator capable of effectively preventing the motion of a stage other than the X-Y plane of motion.
It is a third object to provide a single-stage microactuator that maximizes the storage capacity with the expansion of a stage area due to effective arrangement of structures.
Accordingly, to achieve the above objects, the present invention provides a single-stage microactuator including: a substrate; a fixed plate electrode disposed at a central portion of the substrate; a rectangular stage having first and second direction of sides, which is located above the fixed plate electrode, the second direction being perpendicular to the first direction; a plurality of actuating frame parts provided corresponding to the two first direction of sides and the two second side directions for regions surrounding the stage, wherein each actuating frame includes a plurality of actuating frames arranged parallel to a corresponding side of the stage adjacent to each surrounding region; a plurality of comb normal directional deformable spring parts, each disposed between each side of the stage and the inner part of each actuating frame part, wherein each comb normal directional deformable spring part includes a plurality of spring members extending in a direction perpendicular to a corresponding side of the stage; a plurality of fixed frame parts, each including a plurality of fixed frames alternately arranged parallel to the plurality of actuating frames of a corresponding actuating frame part of each surrounding region; an actuating comb electrode provided in each actuating frame of the actuating frame part, the actuating comb electrode extending in a direction perpendicular to the side of the stage corresponding to each surrounding region; a fixed comb electrode arranged alternately in parallel to the actuating comb electrode in each fixed frame of the fixed frame part; and a plurality of comb directional deformable spring parts disposed on one side of each actuating frame part opposite the stage and the opposing side thereof for providing an elastic recovery force in a direction perpendicular to one side of the stage corresponding to each of the surrounding regions.
In the single-stage microactuator, the actuating frame of each actuating frame part includes: a first actuating main frame arranged parallel to an adjacent side of the stage; a plurality of actuating sub-frames arranged outwardly from the stage and spaced from and parallel to the first actuating main frame; and a plurality of second actuating main frame extending outward from the stage and connecting the first actuating main frame to the plurality of actuating sub-frames.
Preferably, the fixed frame of each fixed frame part includes a plurality of fixed sub-frames arranged parallel to the first actuating main frame and the plurality of actuating sub-frames; and a plurality of fixed main frames for fixing the fixed sub-frame for each region. Preferably, an area surrounding the stage is partitioned into the surrounding regions by boundary lines extending from the stage in a diagonal direction of the stage, and corresponding actuating and fixed frame parts are arranged in a form corresponding to each surrounding region. It is preferable that the plurality of second actuating main frames are arranged in a direction extending radially from the stage, and the plurality of fixed main frames are arranged in a direction extending radially from the stage.
Furthermore, in the single-stage microactuator, a fixed plate electrode pad is disposed at a portion adjacent to an edge of the substrate, and a line electrode extends in a diagonal direction of the substrate for connecting the fixed plate electrode pad with the fixed plate electrode. Preferably, an actuating frame electrode pad and a fixed frame electrode pad are disposed at outer ends of the second actuating main frame and the fixed main frame, respectively, for applying voltages to the actuating frame part and the fixed frame part, respectively.